SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ea5fa397bd673692d8755cac922f958559f2bbf75657234a51172cda731db35' 
  AND token = 'wHQ63ywMQGyCjDY7q67nJxiVAuyqBErioIV3eha7Un0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}